The present invention relates generally to electrical connections, and more particularly to an electrical connector assembly for a printed circuit board.
Numerous connectors exist to facilitate mounting components to circuit boards and to establish electrical interconnections therebetween. One such type of connector is a subminiature connector assembly. Subminiature connector assemblies are integrated atop circuit boards and are generally utilized to connect a cable, such as a coaxial cable, to circuit boards. Such connectors are commonly referred to as SMA, SMB or SMC connectors to designate operation of the subminiature connectors in different frequencies (e.g., of about 18,4 and 10 GHz, respectively).
FIG. 1 illustrates a top view or footprint of a conventional subminiature connector assembly 100 (e.g., SMA, SMB, SMC) that may be integrated onto a circuit board. The connector assembly 100 includes a central through-hole or via 104, which is surrounded by an arrangement of associated vias 108. The vias provide passages that allow corresponding leads (or pins) to pass therethrough to facilitate electrical connections and component mounting to the circuit board. In the example of FIG. 1, the four perimeter vias 108 of the connector 100 typically facilitate a connection to ground, whereas the central hole 104 provides for connecting a central conductor to a power source or other associated circuitry. Respective connector pads 114, 118 surround each of the through-holes. The connector pads are conductive material disposed usually on top and/or on bottom of the circuit board.
A circuit board generally comprises several layers that lie below the connector assembly 100 illustrated in FIG. 1. Such layers include conductive elements, such as conductive traces (e.g., associated with power and/or ground planes), as well as non-conductive material (e.g., dielectric material). Dielectric layers are typically situated between conductive layers to electrically separate the layers. With reference back to FIG. 1, for example, a dielectric layer typically is positioned between the central connector pad 114 and an associated power or ground layer. Such an arrangement, however, often leads to capacitive charging, which can significantly degrade the intended operation and performance of the circuitry associated with the circuit board.
By way of example, it is known that a capacitor consists of two opposed conducting plates separated by an insulating material or dielectric. The resulting capacitance is directly proportional to the surface areas of the opposed plates, and is inversely proportional to the distance between the plates. As such, where a connector pad overlaps or is in close proximity to a conductive layer, and a dielectric layer is interposed therebetween, capacitive build up can result. This effect tends to occur more readily at high frequencies, such as those frequencies within which subminiature connectors usually operate.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention relates generally to a connector pad includes projections extending outwardly from an inner portion of the pad to help stabilize and reinforce the pad and an associated through-hole. The added stability allows the radial thickness of an inner portion of the pad to be reduced relative to other connection pads that may be part of the board. This decreases the surface area of the pad and reduces the opportunity for capacitive build up to occur relative to an associated conductive plane in a circuit board.
According to another aspect of the present invention, the circuit board can include an anti-pad layer in substantially the same plane as the conductive plane, which anti-pad provides a clearance area around the through-hole that can be increased to further separate the pad from the underlying conductive layer. The increase in separation between the pad and the conductive layer further mitigates the opportunity for capacitive build up to occur.
To the accomplishment of the foregoing and related ends, certain illustrative aspects of the invention are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed and the present invention is intended to include all such aspects and their equivalents. Other advantages and novel features of the invention may become apparent from the following detailed description of the invention when considered in conjunction with the drawings.